The present invention relates to a slide arrangement for blocking or closing off a channel that is disposed between a coal pulverizer and coal dust burners, and which guides or conveys a gas having a high proportion of coal dust.
A coal dust/gas mixture having a very high coal dust content of 1,000 g/m3 or more is conveyed in the discharge conduit that leads from the coal pulverizer to the coal dust burners. Due to official regulations, for example the accident prevention regulations, for safety reasons two successively arranged blocking or shut-off means are provided in the discharge conduit, one of which is generally designed as a slide.
Serious problems occur with such slides. For example, all of the components in the channel, and even the channel or housing walls, are subjected to considerable erosion due to the abrasive coal particles. The penetration of coal dust itself through the smallest gap into the shroud of a slide arrangement cannot be prevented due to the very high air moisture of the gaseous conveying medium, and due to the different types of chemical substances in the coal dust, penetrating particles are deposited in the shroud, caked together, and cause considerable corrosion on all of the components or increase the danger of the formation of pools of glowing material, as a result of which a complete inability to operate can occur very rapidly.
A number of constructions have been developed to address the aforementioned problems. These include:                Plug-in disks that are inserted into a gap formed between two flanges due to the withdrawal of a compensator. Such a construction is functional and economical, but is very work intensive and cannot be automated.        Different variations of slides with or without shrouds exist that also permit an automatic operation. However, especially with this group, sooner or later the aforementioned problems occur.        The so-called stuffing box slides form a further group. Here, a flat plate is sealed by a rectangular stuffing box. The non-ribbed slide plate must have an extremely sturdy configuration due to its design for the explosion pressure. Such a construction is acceptable for smaller channels; with larger channels, considerable sealing problems occur due to the expansion of the plate, which damages the seal at the end faces of the plate, which in turn, due to the high underpressure, can lead to considerable contamination in the region of the pulverizers.        Pivot flaps: which are pivoted up into a side channel pocket, have proven themselves in practice, yet have a number of drawbacks. For one thing, the pivot wing, with its seals, is subjected to continuous wear even in the side pockets, and therefore frequently no longer provides an adequate seal when it must suddenly be put into use. For another thing, such a construction requires a large amount of space for the wings that are to be pivoted up. Such space is often in practice not available above the coal pulverizers.        
It is an object of the present invention to embody a slide arrangement of the aforementioned general type in such a way that it is sealed, sturdy, resistant to wear, and resistant to pressure shocks.